Partial liquid ventilation of the critically ill neonate on extracorporeal membrane oxygenation (ECMO) may be tolerated well and may improve either the pulmonary function and or overall clinical course of the infant. The primary purpose of this study is to demonstrate the safety of partial liquid ventilation as measured by changes of greater than 30% in blood gas values (PaO2, PaCO2, BE), urine output, blood pressure,(systolic, diastolic and mean) or heart rate during the acute and extended intervention periods.